Emulsion aggregation toner (E/A Toner) has been developed for digital color copiers & printers.Emulsion aggregation toner has been prepared by using the following process steps: pigment/wax dispersion preparation, emulsion polymerization, homogenization, aggregation, and coalescence. Shape optimized toner particles are obtained by the control of temperature, pH and time.The emulsion aggregation process with stepwise aggregation in particle formation provides a capsule structure and it also exhibits narrow particle size distribution.Narrow size distribution can be obtained by optimization of the latex size and Zeta potential, controlled in the emulsion polymerization step.This study shows the surface controlled toner can provide 2 important advantages for high quality color printing compared to conventional pulverized toner. The first is a method to control the charging of different colors by uniform surface composition. The same level of charge is obtained for each color as well as stable print quality under various conditions. Charging properties can also be controlled by metal ion treatment in the toner-washing step. The second advantage is the prevention of surface wax, which enables high toner flow, even for small particle sizes about (5-micron particle). This process also enables compatibility with an oil-less fusing system and excellent image quality with lower toner mass per unit area even for rough paper surfaces.
Yasuo Matsumura, Patricia Burns, Takashi Fuchiwaki, "Encapsulated Emulsion Aggregation Toner for High Quality Color Printing" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP17), 2001, pp 341 - 344, https://doi.org/10.2352/ISSN.2169-4451.2001.17.1.art00075_1